Due to actualization of environmental problems in recent years, hybrid cars and electric cars have spread. Furthermore, as an air conditioner which is applicable to such a vehicle, there has been developed an air conditioner which comprises a compressor to compress and discharge a refrigerant, a radiator disposed on a vehicle interior side to let the refrigerant absorb heat, a heat absorber disposed on the vehicle interior side to let the refrigerant absorb heat, and an outdoor heat exchanger disposed on a vehicle exterior side to let the refrigerant radiate or absorb heat, and which executes respective operation modes of a heating cycle in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant by which heat has been radiated in this radiator absorbs heat in the outdoor heat exchanger, a dehumidifying and heating cycle in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant by which heat has been radiated in the radiator absorbs heat only in the heat absorber or in this heat absorber and the outdoor heat exchanger, a cooling cycle in which the refrigerant discharged from the compressor radiates heat in the outdoor heat exchanger and absorbs heat in the heat absorber, and a dehumidifying and cooling cycle in which the refrigerant discharged from the compressor radiates heat in the radiator and the outdoor heat exchanger and absorbs heat in the heat absorber (e.g., see Patent Document 1).
Additionally, in the above publication, when the heating cycle and the cooling cycle are changed, the cycle is changed via an internal cycle. This internal cycle has a state where the refrigerant is inhibited from flowing into the outdoor heat exchanger and the refrigerant radiates heat in the radiator and absorbs heat in the heat absorber, and hence as compared with the dehumidifying and heating cycle or the dehumidifying and cooling cycle, a dehumidifying capability further heightens and a heating capability becomes smaller. Therefore, these other types of operation modes (cycles) are changed in accordance with conditions such as an environment and a set temperature, thereby performing comfortable air condition in a vehicle interior.